In the field of medical care, it is known that films are applied to biological tissues for closure of the site of a surgical wound, protection of the site of a burn wound or the like, hemostasis, fixation of a device such as an infusion line to the skin, prevention of adhesion of an organ and the like. Those films are required to have the ability to firmly attach to biological tissue and flexibility or strength that allows the films to follow movement of a living body to prevent bleeding from an opened wound, exposure of the biological tissue, detachment of a device fixed to the biological tissue, organ adhesion, and the like.
In addition, when such films are used in vivo, if a film is permanently left in vivo, it may lead to complications such as infection and inflammation, and it may also result in requiring re-operation to remove the film. It is therefore necessary for the film to be biodegradable so that it is degraded and disappears in vivo after fulfilling its role.
Known biodegradable films include films comprising biodegradable polymers such as polylactic acid, polylactone, and copolymers containing blocks of such polymers. For example, JP Patent Publication (Kokai) Nos. 2014-140978 A and 2012-187926 A each disclose a film comprising a biodegradable polymer and having a nanometer film thickness that can adhere to biological tissue. In addition, JP Patent Publication (Kokai) Nos. 2001-327520 A and 2004-313759 A each disclose a biodegradable film having hydrophilicity and biological affinity that contains a block copolymer.
The films disclosed in JP '978 and JP '926 are, however, highly hydrophobic and therefore they are considered to have a low affinity to the surface of a living body in a humid environment. Further, as a crystalline copolymer having a high glass-transition temperature is used, even when a thin film is made, the film is hardly deformed. Such film cannot sufficiently follow movement of a living body or cannot be adjusted to biological tissue having a fine uneven surface, which has been problematic. In addition, as the films disclosed in JP '520 and JP '759 have high adhesiveness to biological tissues, they have not been examined in terms of film thickness. It is unclear whether they have sufficient properties required when used as an antiadhesive material.
It could therefore be helpful to provide a polymer film that can be adjusted to movement or a fine uneven surface of a living body and has excellent ability to adhere to biological tissue.